Kato Mikado - jerky operation

[Bart1701]

I just replaced the drivers on my first-run Mikado with their revised drivers ( as had been talked about on another recent thread ). It took a while, but I finally got them installed and the electrical pickup is fantastic now! But, the engine no longer runs as smoothly or as quietly as it did before. It makes a very audible "clicking" sound when it runs. It also looks as if it is hopping up and down slightly as it moves. When the locomotive stops in a certain position, I cannot get it to move forward. It is basically stalled in that position. I can put it into reverse at this time, and it will move backwards OK. As long as it hasn't stopped in that one position, it will then move forward OK and continue around the layout.

Does anyone have any ideas what could be causing this and how to diagnose it / solve it?

I have included photos of each side of the locomotive in its "stalled" position just in case that helps.





Thanks,
Bart

[peteski]

Hmmm... that sounds like either the drivers are out of quarter or the drivers have misaligned gear. However, due to Kato's ingenious mechanism design (I still can't get over how clever it is), there is no way that this can happen.

Well, even if the drivers were misaligned by a tooth or to (in reference to each other) that still would not cause any binding as 2 out of 3 driven axles are not attached to the side rods. They would look terribly misaligned but the loco would still run smoothly.

As far as the wheel-set (on the same axle) being out of quarter is again not possible due to a self-aligning axle (which is not round but it is 6-sided (line an Allen wrench).  So either the side rod pins on the opposite ends of each axle are perfectly 90 degrees apart, or they are so badly misaligned (if the wheel is installed incorrectly) that the loco wouldn't run at all.

I think I see a quartering misalignment in the photos but it might just be an optical illusion (because a slight error like that should be impossible on this model).

I would cradle the loco upside down then using test leads with alligator clips hook up a throttle to the tender and while the drivers turn slowly observe the action and look for binding.  You could also remove the siderods (just leave the connecting rods on the 3rd driver and see if the loco still binds.  Again, due to the design, removing the siderods should not affect the running characteristics.

Is it possible that there is a piece of debris stuck on one of the gears on one of the driven axles? That could cause a one-per-revolution cyclical drive binding.

[Wardie]

Is it possible that there is a piece of debris stuck on one of the gears on one of the driven axles? That could cause a one-per-revolution cyclical drive binding.

That sounds like a the most probable cause. I have never taken apart a Kato Mikado drivetrain, but I did have that problem in a diesel once. A little piece of ballast had managed to worm it's way into a gear.

[Bart1701]

Just to make sure I understand the term "quartering" for steam locomotive drivers. On one side of the locomotive, all of the counterweights should be in roughly should be in the same position. On the other side of the locomotive, the counterweights are all in the same position on that side, but they would have their centers aligned at a position that is 90 degrees different than the other side. Does that sound right?

I believe that the wheels on my locomotive are quartered. It appeared that they are delivered in that fashion from Kato. The reverse angles of the two photos I posted may be creating the illusion that they are not quartered. Using a clock as an analogy, the top picture shows the counterweights center aligned at the 7 o'clock position. If you could look straight through to the other side, those counterweghts are center aligned to the 4 o'clock position (as determined from the first side). 3 hours on a clock would be 1/4 of the clock face, or 90 degrees.

I will look closely at the gears to see if there is any debris on them.

If anyone else has any other thoughts or suggestions on what I should be looking for, please let me know.

I have always appreciated everyone's advice to any problems or questions I have posted on this site!

Bart

[peteski]

Just to make sure I understand the term "quartering" for steam locomotive drivers. On one side of the locomotive, all of the counterweights should be in roughly should be in the same position. On the other side of the locomotive, the counterweights are all in the same position on that side, but they would have their centers aligned at a position that is 90 degrees different than the other side. Does that sound right?

Yes, correct.

I believe that the wheels on my locomotive are quartered. It appeared that they are delivered in that fashion from Kato. The reverse angles of the two photos I posted may be creating the illusion that they are not quartered. Using a clock as an analogy, the top picture shows the counterweights center aligned at the 7 o'clock position. If you could look straight through to the other side, those counterweghts are center aligned to the 4 o'clock position (as determined from the first side). 3 hours on a clock would be 1/4 of the clock face, or 90 degrees.

Like I said, the photo makes the counterweights (on the same side) look slightly misaligned.  But (for the reasons I mentioned initially) it is pretty much impossible to have a Mikado with slightly out of quarter drivers.  So yours must be ok.

EDIT: I looked again at this photo:


The counterweight on the front driver seems off compared to the other 3 drivers. Doesn't it?

[u18b]

Actually, I was thinking the #2 driver is rotated clockwise one gear tooth.

Study the angle made by the flat part of the counter weight and the rail.

I do agree they do not all look uniform.

Edit with further thought:  In fact, I agree.  Let's assume the #3 and 4 are the standard since they look the same.

The #2 driver looks ahead one tooth to the standard and the #1 looks one tooth behind.

Which means #1 and 2 may have two teeth difference.

[peteski]

But even if the teeth are misaligned (which might be the case), that will not introduce any binding at the siderods (because of the way this mechanism is constructed).  Binding could occur if the right and left sides of either the front or the 3rd driver were out of quarter (not 90 degrees apart) but I suspect that Bart just installed them as the come from the factory.

[superchief]

to my eyes the front two drivers and the rear two drivers are ONE tooth off/ that being said with the side rods not connected but at the 3rd driver, i think there is a very small piece of debris in a gear/ i would taken the bottom plate off and rotate the drivers that should fix it! Gordon......good luck those engines are puzzles!!

[mike_lawyer]

First, pop the motor and worm out of the locomotive and see if you can move the drivers by hand. 

Second, if the drivers stop at a particular point, turn the locomotive over in an engine cradle.  Remove the gear plate.  Remove the second driver, then re-install the cover plate.  Then try moving the drivers by hand.  Repeat this process for drivers 3 and 4, each time removing only one driver.  What you are trying to do is see if one of the geared drivers has a damaged tooth.  If after removing one of drivers 2-4 the problem goes away, the problem might be a damaged gear tooth.

Finally, you might also have a damaged idler and/or compound gear.  I have had this problem before.  The good news is that you can order replacement idler and compound gears directly from Kato.

Mike

[SkipGear]

It has to be debris in a gear.

By the design of the loco, you can have the geared drivers in any orientation you want, it will look funny but the loco will still run just fine. The siderods are only connected to axle #1 and #3. Axle #1 is driven by the side rods only. Axles #2, 3, & 4 are all gear driven but #2 and #4 are not connected to anything. They can be rotated any position you want and the loco will still run perfectly smooth.

[peteski]

It has to be debris in a gear.

By the design of the loco, you can have the geared drivers in any orientation you want, it will look funny but the loco will still run just fine. The siderods are only connected to axle #1 and #3. Axle #1 is driven by the side rods only. Axles #2, 3, & 4 are all gear driven but #2 and #4 are not connected to anything. They can be rotated any position you want and the loco will still run perfectly smooth.

That's what I stated earlier (with slightly different wording). I think we might all be onto something. 

[UP4-8-8-4]

   As was mentioned, Katos Mikado is the easiest to put the traction tire driver set on.
It dosn't make any difference if that driver set is quarted or now, just quarter it for looks.
You might have lifted and moved the driver set beside it a tooth off when placing the TT driver set in.
Might pull and check the TT driver sets gear and be sure theres not a burr somewhere on one of the teeth. Easily filed off is there is one.
Have replaced TT driver sets before that had a small burr.
Also check all the side rods, might have slightly bent one.



Ernie

[Bart1701]

Problem solved 

It turned out to be a damaged tooth on a gear on one of the new axles. That should explain the slight "hopping" and the loud clicks that were occurring. When the damaged (almost missing) tooth came into contact with the other gears, I can see where that gear would have wanted to skip ahead a bit faster than the other gears causing the locomotive to hop and click.

I replaced the defective axle/gear with one of the original ones and the engine moves along smoothly and quietly now.  I'll work with Kato to see if they can replace the axle with the damaged gear. Since it acted this way as soon as I had installed the new drivers, I am thinking that the gear must have been damaged from the start. I can't see that there was anything I did that would have caused the gear tooth to become damaged.

Thanks for everyone's help, and also explaining quartering to me. I agree that some of the wheels on each side may not be in perfect alignment. They're close, but not perfect. I'll work on getting those aligned better when I get the replacement axle.

Bart

[SkipGear]

That's what I stated earlier (with slightly different wording). I think we might all be onto something. 

I knew you were on the right track....others kept hanging on the quartering issue and I was trying to explain why quartering didn't matter.